Numerous prior art devices have been disclosed which are used for lifting a vehicle for servicing, repairing or storing vehicles. However, there are many problems inherent with the known lifting devices, such as safety, functionality and durability. Due to the size, weight and bulk of an automobile, lifting devices must be sturdy, reliable and safe.
Devices commonly used to lift a vehicle for service or repair have a large, centrally positioned piston or ram, mounted in the floor or ground. When activated, the typical device will hydraulically lift the vehicle off the ground. These devices, while generally safe, limit accessibility to the underside of the lifted vehicle due to the size and central location of the piston.
Another type of known vehicle lift is referred to as a cantilever lift. These devices utilize a pair of opposed stanchions, generally located near one end of the vehicle lift. The vehicle is driven onto a platform or pair of ramps between the stanchions. A lifting mechanism, generally hydraulic or screw driven, is located at one end of the platform or ramp. Stanchions are preferred because they are generally positioned near one end of the device and allow unrestricted access to the door of the vehicle once it is driven onto the platform or ramps.
The use of such stanchions leads to problems. In particular, the force applied to the cantilever lifting mechanism is not uniform or directional. As safety is always a major concern when lifting a vehicle off of the ground, it is necessary to evaluate the application and direction of force imposed on the lifting device by the weight of the vehicle. The cantilever type of car lifts have known safety problems. It is not uncommon for the end of the platform opposite the stanchions to sag, allowing the vehicle to roll or slide off, or even to collapse. Further, constant stress imparted on the lifting device from the weight of the vehicle tends to weaken the structural integrity of the device and results in undesirable maintenance and repairs.
Efforts directed to modifying the typical two-stanchion cantilever car lift have resulted in increasing the number of stanchions, or changing the location of the stanchions. Increasing the number of stanchions, or moving the stanchions to a central position, has improved safety and reliability of the vehicle lifting device. This arrangement is still not preferred because the weight of an elevated vehicle makes it desirable to have a sturdy lifting device and it is preferable to have the vehicle supported at each corner.
Heavy items, when elevated, lose stability and become difficult to move. It is often necessary to move a vehicle while on a lift, for storage purposes or to accommodate mechanical repairs. If the vehicle is not operational, it is difficult to remove it from the lift, move the lift and then replace the vehicle. The simple solution is to provide a vehicle lift which can be easily moved with a vehicle in place. Even though some of the cantilever type car lifts are provided with wheels or casters, when a vehicle is on the lift and elevated, it is difficult to move and the likelihood of the vehicle coming off of the lifting device is high.
An alternative arrangement being used has four post lifts located at the approximate four corners of the device. By positioning a post at each corner of the lift device and supporting a vehicle on a platform or ramps supported between the post, a stable environment may be achieved for working under the suspended vehicle or for storing a second vehicle under the suspended vehicle. Generally, four post lift devices are powered by at least one mechanical screw assembly which alternately raises and lowers the platform or ramps depending on the direction of screw rotation. Some four post devices utilize one or two vertically positioned hydraulic rams at, or near, the posts and push or pull, depending on orientation, the vehicle into a lifted position.
Another variation of the four post lift is the hydraulically powered cable lift. These devices generally utilize one or more cables, attached to the outer periphery of each corner post, and strung through a series of pulleys and attached to a hydraulic ram. When the ram is activated, vertical elevation of the vehicle is achieved. Universally, regardless of the type of lifting device, there are exposed working parts. The various driving mechanisms found on lifts, such as: screw assemblies, hydraulics and gears and chains are generally attached to the outside of one or more of the stanchions or posts. These parts account for injuries to operators, damage to the vehicles, accumulation of dust and dirt, and tend to wear quickly due to exposure to the elements.
A significant disadvantage of known four post lifts is the manner in which the lifting mechanism applies the force necessary to elevate a vehicle. Typically, the lifting mechanism will include a series of cables and pulleys fastened on the outer surface of each column. A common attachment point for the lifting cables is on an overhanging outside edge of a top cap, typically fashioned of plate metal. The position of the cables on the outer edge of the top cap results in significant directional force applied unevenly away from the center of each column when a vehicle is elevated.
The positioning of the cables on the outside perimeter of each column decreases the stability and safety of the vehicle lift. In instances where the columns are not fastened to the ground, or suitable flooring, the inward directional force may lead to collapse of the device. Further, the connection point of the cables, as well as related parts of the device, are under constant angular strain, resulting in rapid wear, distortion or failure of components.
What is needed is a vehicle lift which is stable and durable. Further, it is desirable to provide a vehicle lift which is easy to use, which is safe and has very few exposed moving parts which could injure the operator.